Have recently moved into a flat with underfloor heating. Heating runs on economy 7. and switching is controlled by synchronous timer. Problem is that the timer has stopped working and only did so after plumber had switched off consumer unit when doing a job on the immersion heater. Have checked the fuse to the timer and is OK. Any suggestions? Is there a reset button anywhere? Timer was installed in the early 80's and has been working fine until now.